[ltt-dev] net extended trace openin error with LTTV (without attachment)
Benjamin Poirier
benjamin.poirier at polymtl.ca
Mon Feb 8 16:30:43 EST 2010
Mathieu Desnoyers wrote:
> * Benjamin Poirier (benjamin.poirier at polymtl.ca) wrote:
>
>> paljak at mit.bme.hu wrote:
>>
>>> -----Mathieu Desnoyers <compudj at krystal.dyndns.org> wrote: -----
>>>
>>> To: paljak at mit.bme.hu
>>> From: Mathieu Desnoyers <compudj at krystal.dyndns.org>
>>> Date: 2010/02/08 16:36
>>> cc: benjamin.poirier at polymtl.ca, ltt-dev at lists.casi.polymtl.ca
>>> Subject: Re: [ltt-dev] net extended trace openin error with LTTV
>>> (without attachment)
>>>
>>> * paljak at mit.bme.hu (paljak at mit.bme.hu) wrote:
>>> > Hi Ben,
>>> >
>>> > I have been working with LTTng lately and the more I know it, the
>>> more I
>>> > like it!
>>> >
>>> > I've also been able to open and examine traces, and it looks very
>>> > interesting.
>>> >
>>> > I've also tried to create my own, but I've ran into an error,
>>> could you
>>> > take a look?
>>> >
>>> > Basically, I receive an error
>>> > (ERROR:tracefile.c:1582:ltt_update_event_size: assertion failed:
>>> (info !=
>>> > NULL)) every time i try to open a net_extended trace with LTTV.
>>> >
>>> > Here's what i've done:
>>> >
>>> > 1. Downloaded the patched kernel: git clone
>>> >
>>> git://git.kernel.org/pub/scm/linux/kernel/git/compudj/linux-2.6-lttng.git
>>> > 2. Compiled the kernel with these options (.config):
>>> > #
>>> > # GCOV-based kernel profiling
>>> > #
>>> > # CONFIG_GCOV_KERNEL is not set
>>> > CONFIG_SLOW_WORK=y
>>> > # CONFIG_SLOW_WORK_DEBUG is not set
>>> > CONFIG_LTT=y
>>> > CONFIG_LTT_FILTER=m
>>> > CONFIG_HAVE_LTT_DUMP_TABLES=y
>>> > CONFIG_LTT_RELAY=y
>>> > CONFIG_LTT_RELAY_LOCKLESS=y
>>> > # CONFIG_LTT_RELAY_IRQOFF is not set
>>> > # CONFIG_LTT_RELAY_LOCKED is not set
>>> > CONFIG_LTT_SERIALIZE=y
>>> > CONFIG_LTT_FAST_SERIALIZE=y
>>> > CONFIG_LTT_TRACEPROBES=m
>>> > CONFIG_LTT_TRACE_CONTROL=y
>>> > CONFIG_LTT_TRACER=y
>>> > CONFIG_LTT_ALIGNMENT=y
>>> > CONFIG_LTT_CHECK_ARCH_EFFICIENT_UNALIGNED_ACCESS=y
>>> > # CONFIG_LTT_DEBUG_EVENT_SIZE is not set
>>> > CONFIG_LTT_USERSPACE_EVENT=m
>>> > CONFIG_LTT_VMCORE=y
>>> > CONFIG_LTT_STATEDUMP=m
>>> > CONFIG_LTT_KPROBES=m
>>> > # CONFIG_LTT_ASCII is not set
>>> > 3. Install the kernel and boot it up
>>> > 4. Load all the modules
>>> > modprobe -v ltt-trace-control
>>> > modprobe -v ltt-marker-control
>>> > modprobe -v ltt-tracer
>>> > modprobe -v ltt-serialize
>>> > modprobe -v ltt-relay
>>> > modprobe -v ipc-trace
>>> > modprobe -v kernel-trace
>>> > modprobe -v mm-trace
>>> > modprobe -v net-trace
>>> > modprobe -v fs-trace
>>> > modprobe -v jbd2-trace
>>> > modprobe -v ext4-trace
>>> > modprobe -v syscall-trace
>>> > modprobe -v trap-trace
>>> > modprobe -v ltt-statedump
>>> > #extended trace
>>> > modprobe -v net-extended-trace
>>> > 5. ltt-armall -n
>>> > 6. lttctl -C -w /tmp/tr1 tr1
>>> > 7. wget http://google.com
>>> > 8. lttctl -D tr1
>>> > 9. lttv -m textDump -t tr1
>>> > **
>>> > ERROR:tracefile.c:1582:ltt_update_event_size: assertion failed:
>>> (info !=
>>> > NULL)
>>> > /usr/local/bin/lttv: line 15: 2083 Aborted $0.real $*
>>> > 10. lttv -m textDump -t tr1 --verbose --debug --edebug
>>> > net.udpv4_rcv_extended: 1003.743082325 (/tmp/tr1/net_0), 1878, 1878,
>>> > gnome-terminal, , 1, 0x0, SOFTIRQ { skb = 0xC4BBC240, saddr =
>>> 3576624693,
>>> > daddr = 3232235780, unicast = 1, ulen = 110, source = 53, dest =
>>> 39087,
>>> > data_start = a299884901000100 }
>>> > Event header (tracefile /tmp/tr1/net_0 offset bb8):
>>> > bb8 40 C2 BB C4
>>> > **
>>> > ERROR:tracefile.c:1582:ltt_update_event_size: assertion failed:
>>> (info !=
>>> > NULL)
>>> > /usr/local/bin/lttv: line 15: 2104 Aborted $0.real $*
>>> >
>>> > The installed versions are:
>>> > Linux Trace Toolkit Visualizer 0.12.29-02022010
>>> > Linux Trace Toolkit Trace Control 0.79-01022010
>>> >
>>> > Here's the created trace for reference:
>>> > http://www.mit.bme.hu/~paljak/trace.tgz
>>> <http://www.mit.bme.hu/%7Epaljak/trace.tgz>
>>> >
>>> > If I don't use net extended, than it works just fine. And I've
>>> also had
>>> > success open your example trace.
>>> >
>>> > Do you have any idea why do I get this error and how could I
>>> correct it?
>>>
>>> That looks like a field type error in the net extended event. Can you
>>> tell us what LTTng version you use ? (git branch should tell you)
>>>
>>> Is your traced machine 32 or 64 bits ? And what about the machine
>>> running lttv ?
>>>
>>> Reviewing ltt/probes/net-extended-trace.c might help.
>>>
>>> Thanks,
>>>
>>> Mathieu
>>>
>>> I use lttng-0.188. And I run lttng and lttv on the same, 32 bit machine.
>>>
>>> I'm checking net-extended-trace.c but reason I could think of to cause
>>> this error...
>>>
>>>
>> I can't reproduce the problem, but looking at the traces, I notice the alignment is different:
>>
>> your trace:
>> metadata.core_marker_id: 994.751622140 (/tmp/trace/tr1/metadata_0), 0, 0, , , 0, 0x0, MODE_UNKNOWN { channel = "net", name = "udpv4_rcv_extended", event_id = 2, int = 4, long = 4, pointer = 4, size_t = 4, alignment = 4 }
>>
>> my trace:
>> metadata.core_marker_id: 193.282545152 (/tmp/tr1/metadata_0), 0, 0, , , 0, 0x0, MODE_UNKNOWN { channel = "net", name = "udpv4_rcv_extended", event_id = 2, int = 4, long = 4, pointer = 4, size_t = 4, alignment = 0 }
>>
>> Could you apply the following patch over the git kernel, build and test? Thanks.
>>
>
> Seem like my LTTng patch:
>
> lttng-trace-format-allow-large-alignment.patch
> "lttng trace format allow large alignment
>
> Do not limit alignment on architecture size anymore, because uint64_t
> types are
> aligned on 64-bit even on 32-bit archs. It's a waste of space for 32-bit
> architectures, but makes our format compatible with gcc."
>
> does not do everything it needs to do. Or maybe LTTV still do an
> alignment on min(arch size, data size) somewhere.
>
> A way to "just amke it work" is to disable alignment in LTTng. But it
> would be good to find the culprit.
>
Indeed, I have CONFIG_LTT_ALIGNMENT=n in my kernel, lucky me! If I
activate it I can reproduce the problem and the patch I suggested
doesn't change it, so don't bother. Disable alignment in the meantime as
suggested by Mathieu.
-Ben
> Thanks,
>
> Mathieu
>
>
>
>> diff --git a/ltt/probes/net-extended-trace.c b/ltt/probes/net-extended-trace.c
>> index 074bfec..88410f8 100644
>> --- a/ltt/probes/net-extended-trace.c
>> +++ b/ltt/probes/net-extended-trace.c
>> @@ -130,14 +130,14 @@ notrace void probe_udpv4_rcv_extended(struct sk_buff *skb)
>> * bytes of UDP data if they are not in a fragment*/
>> data.f8 = 0;
>> if (skb_headlen(skb) >= sizeof(struct udphdr) + 8)
>> - data.f8 = *(unsigned long long *)(skb->data + sizeof(*uh));
>> + data.f8 = *(uint64_t *)(skb->data + sizeof(*uh));
>> else if (skb_headlen(skb) >= sizeof(struct udphdr))
>> memcpy(&data.f8, skb->data + sizeof(struct udphdr),
>> skb_headlen(skb) - sizeof(struct udphdr));
>>
>> marker = &GET_MARKER(net, udpv4_rcv_extended);
>> ltt_specialized_trace(marker, marker->single.probe_private,
>> - &data, serialize_sizeof(data), sizeof(unsigned long long));
>> + &data, serialize_sizeof(data), sizeof(uint64_t));
>> }
>>
>> MODULE_LICENSE("GPL and additional rights");
>>
>>
>>> Thanks,
>>> Gergely
>>>
>>>
>>> ------------------------------------------------------------------------
>>>
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